The Use of Rice Husk Powder in Composites Cement System
CHAPTER ONE
Objectives Of Study
- Determining the compressive strength of the composite by using standard compressive strength testing
- Identifying the crystal phases of the hydration products by x-ray diffraction
CHAPTER TWO
Literature Review
Origin of Cement
Cement can be described as a material with adhesive and cohesive properties which make it capable of bonding mineral fragments into a compact whole. This definition embraces a large variety of cementing materials, but for constructional purpose, the meaning of the term “cement” is restricted to the bonding materials used with stones, sand, bricks, building blocks, etc. (Neville,1981).
The use of cement dates back to antiquity and one can only speculate as to its discovery. Cement was used by the Egyptians in constructing the Pyramids while the Greeks and Romans used volcanic tuff (paste) mixed with lime for cement. This was the first concrete history. (Austin,1984). The active silica and alumina in the ash combined with lime to produce what became known as pozzolanic cement from the name of the village Pozzuoli, near Vesuvius, where the Volcanic ash was first found. The name “Pozzolanic cement” is used to this day to describe cements obtained simply by grinding of natural materials at normal temperature. A number of the Roman structures in which masonry was bonded by mortar, such as the coliseum in Rome, the point du Gard near Nimes and concrete structure such as Pantheon in Rome have survived to this day, with the cementatious material still hard and firm. (Lawali, 2007) In the ruins at Pompeii, the mortar is often less weathered than the rather soft stone. The middle Ages brought a general decline in the quality and the use of cement, and it was only in the eighteenth century that an advance in the knowledge of cements occurred. John Smeaton, commissioned in 1756 to rebuild the Eddystane Lighthouse, off the Cornish coast, found that the best mortar was produced when Pozzolana was mixed with limestone containing a considerable proportion of clay matter. By recognizing the role of the clay hitherto considered undesirable, Smeaton was the first to understand the chemical properties of hydraulic lime that is a material obtained by burning a mixture of lime and clay. (Lawali, 2007).
There followed a development of other hydraulic cements, such as the ‘Roman Cement’ obtained by James Parker through Calcining nodules of argillaceous limestone, culminating in the patent for “Portland Cement” taken out by Joseph Aspdin, a Leeds Bricklayer, stone mason and builder, in 1824. The cement was prepared by heating mixture of clay and hard limestone in a furnace until all the CO2 had been driven off. This temperature was much lower than that necessary for clinkering.The prototype of modern cement was made in 1845 by Isaac Johnson, who burnt a mixture of clay and chalk until clinkering, so that the reactions necessary for the formation of strongly cementitious compounds took place. Portland cement recognizes addition of gypsum after burning but nowadays other materials may also be added or blended. (Lawali, 2007).
Ceramics and Glasses
The term “ceramics” is applied to a range of inorganic materials of wide uses and are non-metallic and in most cases have been produced at high temperature. The word “ceramic” is derived from the Greek “Keramos” or “potter clay” though the group of materials now so described includes glass products; cements and plastics: some abrasive and cutting tools materials, building materials, refractory linings for furnaces, porcelain and other refectory coatings for metals. (Higgins,1998).From the point of view of composition and structure ceramics can be classified into four main groups namely: Amorphous ceramic, Crystalline ceramics, Bonded ceramics and Cements.
CHAPTER THREE
Materials and Methods
Rice husk was collected from Basawa rice mill, Basawa Village, Sabon Gari Local Government area, Kaduna State, Ordinary Portland Cement Used in the study was the Sokoto cement brand, a product of Cement Company of Northern Nigeria (CCNN). Laboratory rotary mill of Nigerian Institute of Leather and Science Technology was used. Other materials such as Tampling Rod, Sampling Equipment (Scoop and Shovel, trowel, Containers like measuring cylinder, moulds and sieves), Capping compound (a moist storage cabinet or room), Compressive Strength Testing Machine, Curing chamber, were provided by the Concrete Laboratory section of Building Department of the Ahmadu Bello University, Zaria. X-ray Diffractometre (software driven) and Mortar and Pestle were sourced from Engineering Materials Equipment Development Institute Akure, Ondo state.
Preparation of rice husk powder
Rice husk powder was prepared by grinding the rice husk in a rotary mill. The powder produced was sieved with British Standard sieves and were allowed to pass through 2µm sieve.
Production of Specimens
The cement was mixed with the rice-husk powder and the control mix without the powder. Both were measured and mixed with water after determining the water/cement ratio. The cube moulds were made of steel and wood in two halves and bolted together. The moulds were kept clean and lubricated with oil to prevent concrete from sticking to the mould. The sections were each time bolted tightly together and they were held down firmly on the base plate. The moulds used are of 70mm x 70mm in accordance with B.S 1881. The mixing was performed in accordance with B.S 1881. This required that mixing should be performed thoroughly to ensure all the constituent materials were uniformly distributed throughout the whole mix. The mixing was done manually with shovel on clean flour in the concrete flow of the concrete laboratory of the Department of Building Ahmadu Bello University, Zaria. The compressive strength of the sample was determined in accordance with the standard procedure for pre-cast concrete block. The weights of the samples were always taken before the compressive strength test was conducted. Three samples blocks were cured each at 28 days after casting at different replacement levels.
CHAPTER FOUR
Results and Discussion
Discussions
Compressive strength
From table 4.1, it can be seen that at 28 days sample A10 has the highest 28 days compressive strength (33.33N/ mm2 water cement ratio (w/c) = 0.32 and Samples A2 and A3 have 19.72N/mm2 and 11.57N respectively. The British Standard BS 12 minimum strengths at 28 days is 29 N/mm2 and water/cement ratio (w/c) is 0. 4. (Bye 1990). Sample A2 gave about 65% of the minimum standard value this is due to effect of surface area and water/cement ratio and could only have potential for non-load bearing application.
X-ray diffraction analysis
Results of the x-ray diffraction analysis of the some of the samples, representing the composites with higher percentage replacement are presented in table 4.2. The results compared the observed crystals phases in the XRD spectrum peaks of the control sample with that of the higher replacement samples (Samples A8, A9, A10 and A11).
Table 4.2 shows crystal structures matched in accordance with the ICCD data. Samples A, A8 and A9 shared similarities in crystal phases and crystal system and this means similar formula (Ca3SiO2) or C3S (Bye, 1990). The observed Overlapping of crystal Systems with indication for monoclinic structures (ICDD cards no; 24-0198,41-1420 and 20-0376 ) verify present of C3S the main strength-producing constituent of cement (Austin, 1984). Mg 2+, Al3+Fe3+ with smaller amount of K+ and Na+ are the most frequently found foreign ions in C3S phase (Bye, 1990) and they were found in across the samples. Samples A10 and A11 have the same crystal systems which are hexagonal structures (ICDD cards no; 38-0395 and 30-170).
CHAPTER FIVE
Summary, Conclusion and Recommendation
Summary
The study was able to explore some of the rice husk in Basawa, Sabongari Local Government Area Zaria. Of much interest in the study are the results of the compressive strength and x-ray diffraction analyses. The 28 days compressive strength of the cubes made reveals that Basawa Rice husk has potential as partial replacement of ordinary Portland cement (Rice-husk Portland cement composite). However, the x-ray diffraction analysis pattern indicates that higher percentage replacement can be achieved only at higher curing period.
Conclusion
The important findings of the study focused more on the compressive strength and x-ray diffraction analyses. However, it can be said that rice husk powder can be used in the production of composite cement particularly for low load bearing concrete and the percentage of the rice husk needed should be between 5-10% and for higher percentage (that is between 10%-50%) no pozzalanic reactions were observed.
Recommendation
The significance of cements in national development need not to be over-emphasized, in view of this, the researcher wishes to make the following recommendations:
- Long term strength development of the composite cement beyond 28 days should be investigated in future studies, e.g. 90 days and 1
- Since curing conditions affect pozzolanic reactivity, the composite cements concrete should be studied in details under various curing conditions in future research
- X-ray diffraction is of limited value in examining the hydration products because variation in their quantity significantly influence diffracted intensity, so more research should be carried out by using scanning electron
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- Dashan I.I.and Kamang E.E.I. (1999). “Some characteristic of RHA/OPC concretes. In: Oyetola E.B. and Abdullahi, M. (2009): The use of Rice husk ash in low cost sand Crete Block production http//lejpt.academic.direct.org/A08/5870.htm accessed on 10/26/2009.